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Page 10 of 907 Results 91 - 100 of 9067

Yuan Liu, Heming Hu, XueLing Qiu, Deyue Zou
Evaluation of ADCP Streamflow Measurements in Open Channel

The purpose of this paper is to explore the potential of calibration of ADCP discharge measurement in open channel, which conclusion can improve the traceability of ADCP. In this paper, the current velocity and discharge synthesis and other important issues are taken into consideration, and establishes a set of rectangular open channel standard discharge facility, and conducts experimental research on the flow measurement by using Workhorse. The moving boat ADCP measurement uncertainty source is analyzed, and the error situation introduced by the approximate solution is analyzed. By estimating the back scattering intensity, a new type of acoustic reflector is designed, so that the signal quality of ADCP can be kept in the best state in the process of towing calibration, so as to ensure the reliability of the WT measurement results. An experimental device for WT, BT, depth measurement is established to evaluate the basic performance of the instrument. At last an ultrasonic transit time flow-meter(UFM) is taken as reference in field situation, to calibrate the discharge directly, the results are close to laboratory calibration.

Han Zhang, Liang Wang, Xinli Dong, Donghong Huang,Peijuan Cao, Yong Li, Ronghui Shang, Shihui Zeng, Xuejian Li
The City Gas Flow Standard Facility within (2~4) MPa

In order to meet the traceability requirements of city gas flow meters, the city gas flow standard facility was built based on master meter method. As the non-fixed usage of master meters and the low temperature of natural gas, the uncertainty evaluation and control of the standard facility were investigated. The results showed that the standard facility used four turbine flowmeters as master meters and has mobility, while the achievable flowrate range is within (60 ~ 8600) m³/h and the pressure range of (2 ~ 4) MPa. The uncertainty of the non-point usage of the master meters was controlled based on the curve fitting method, while the uncertainty of the city gas flow standard facility was 0.26 % (k = 2). Compared with NIM-2014, NIM-2015 was more suitable for master meters with scattered error curves. On this basis, the heat transfer model of the cryogenic natural gas flow in pipeline was established. It was found that the dynamic temperature balance of the facility can be achieved through a longer pre-flow time, which can improve the measurement repeatability. The uncertainty of the calibrated flowmeter is 0.32 % (k = 2). In addition, the comparison experiment with NIM verified the above results.

Biyu Zhu, Chao Chen, Li Ma
Study on the Comparison of Three Typical Gas Flow Standards for Calibrating Low Gas Flowmeter

A gas flowmeter for measuring low flow rate has been widely used in the field of medical, health, environmental protection, energy industry, aerospace, etc. To against Covid-2019, the requirement on the low flow rate has been increasing dramatically. At present, the typical standard devices for calibrating low gas flowmeter mainly include standard bell provers of gas flow, standard piston provers of low gas flow and standard laminar of low gas flow. Different measuring principles are adopted among these typical standard devices. To ensure the consistency of these typical standard devices, a comparison test is performed. The standard devices used in the comparison are of the same accuracy grade, with an extended uncertainty of 0.2 %(k = 2). The piston-type gas flow calibrator of grade 1.0 is selected as the transfer standard, and three flow points with high flow rate, medium flow rate and low flow rate are selected for test. The consistency of measurement results is evaluated by normalized deviation En. The comparison results are acceptable which show that three typical standard devices are accurate and reliable.

F. Arpino, L. Canale, M. L. Cassano, G. Cortellessa, M. Dell’Isola, G. Ficco, A. Tagliabue, F. Zuena
Link between unaccounted for gas in transmission networks and flow-meters accuracy

One of the main issues in natural gas transmission networks is represented by the so-called Unaccounted-for-Gas (UAG), that is the amount of gas related to the unavoidable measurement and estimation errors in the balancing equation of the network. In particular, accuracy of flow-rate measurement in transmission network pipelines is a very crucial issue due to the numerous related metrological criticalities. This paper is aimed at evaluating the influence of the flow-meter accuracy on UAG. To this aim, the rangeability limits of the flow-rate measuring device in delivery points characterized by large fluctuation of gas flows have been investigated, together with the effect of the drift of the instrument due to the absence of punctual periodic calibrations. From the analysis carried out, it was found that about 12 % of the average daily flow rates measured at DSO measuring plants is below the minimum flow rate of the meter and that a significant correlation between monthly UAG and registered rangeability faults of flow-meters has been found.

Huancheng Yang, Jiamin Zhao, Hongyan Geng, Xiaocheng Xu, Min Zhang
Study of Calibration System for Liquefied Natural Gas (LNG) Dispenser Verification Device Based on Quality Method

To fulfil calibrating of LNG dispenser verification device, the traceability system of the device was researched in this paper. Using a combination of dynamic and static quality measurement system, with high accuracy electronic balance as main standard, ultra-low temperature commutator with uncertainty of better than 1.5 × 10-4 was developed. The device could realize automation during the whole procedure of data collection under the specified flow, the calibration of LNG dispenser verification device, processing the data and generating the records and certificates.

Xingen Wang, Yuming Shen, Chaojian Tao, Fuwei Wu
Review on Computation Models of High-Pressure Hydrogen Compressibility Factor

Several computation models for calculating the compressibility factor of high-pressure hydrogen are discussed,including linear equation, Virial Equation, Van der Waals Equation and Redlich and Kwong Equation. ConvertingNIST hydrogen density data to compressibility factor data, the compressibility factor data calculated by the models are compared with NIST data. The computation accuracy of Redlich and Kwong’s Equation is less than 1 % in a wide range of temperature and pressure. The hydrogen compressibility factor data from NIST can be fitted into a linear equation with linear error < 0.55 % when p/T ≥ MPa/K

Q. Pan, W. D. Lin, Y. Liu, L. Q. Zhang, J. M. Wang, J. Peng
Traceability of ultrasonic transit time based on relative displacement method

The increasing demand for ultrasonic flow meter (UFM) is due to the absence of moving, protruding parts projecting into the measured flow, transient response, high accuracy and wide range, so that it becomes important in flow measurement. By analyzing the error sources and magnitude of measurements in water, considering the uncertainty caused by sound speed profile and standard length, comprehensively. This research proposes a method to trace the transit time to standard length. Firstly, based on the servo driving and automatic displacement control, a facility which can provide displacement with a minimum displacement step of 10 μm, is designed, and has been precisely calibration by laser interferometer. The error function of water temperature uniformity on transit time measurement is evaluated by theoretical model. A high-precision constant system is developed to control the temperature gradient in water better than 5mK, and the Anton Paar MKT50 platinum wire resistance thermometer is being used as the temperature standard. Assuming that the ultrasonic waveform does not change during propagation in water. The transit time for multiple reflections between fixed stainless steel protective layer and movable reflector is measured. The time difference between two different reflections of same wave can be obtained by high-precision cross-correlation algorithm, and the center frequency of the first five cycles are calculated through Hilbert transform. Through the linear increasing experiments, the effects of reflection times, path length and test temperature to the measurement of transit time are compared.

S. H. Lee, J. Rauch, B.-R. Yoon
Bilateral comparison of viscosity measurement standard system between KRISS and PTB

This study was conducted to compare the viscosity measurement standard systems of the KRISS and PTB, as well as to confirm the international equivalence of the standard viscosity measurement system built in the KRISS. The KRISS constructed a viscosity measurement standard system using an Ubbelohde-type capillary viscometer. In the KRISS, the viscometer was calibrated based on the water viscosity standard ISO TR 3666, and 16 viscometer coefficients were obtained using the step-up method. The measured viscosity was corrected by evaluating the surface tension, buoyancy, and kinetic energy. The uncertainty of the measurement system, including the temperature and measurement time, was evaluated. The measurement range of the viscosity measurement standard system was 0.3 to 100000 mm2/s, with 0.13%-0.5 % uncertainty (U, k = 2). A bilateral comparison of the viscosity measurement standard system between KRISS and PTB was conducted using three different viscosity standard liquids (5A, 2000A, and 50000A) synthesized by the PTB. The viscosity of the standard liquid was measured at three different temperatures (15 °C, 20 °C, and 40 °C), and comparisons were performed under all six experimental conditions (5A/15 °C, 5A/20 °C, 2000A/20 °C, 2000A/40 °C, 50000A/20 °C, and 50000A/40 °C). By considering the uncertainty, the calculated En was less than 1 (0.17-0.72) for all experimental cases. Therefore, it was confirmed that the recently constructed viscosity standard system of the KRISS exhibits mutual equivalence with the viscosity measurement standard system of the PTB. In the future, KRISS will register the viscosity measurement standard system in a CMC based on the results of this bilateral comparison.

D. L. Liu, Q. Cai, J. Wang,H. M. Hu
Influence of Medium Type on Measurement Performance for Vortex flowmeter

The verification medium of vortex flowmeter in the laboratory is often different from the actual measurement. It is very important and necessary to quantitatively analyze the influence of the medium type on its measurement performance. So it is very important and necessary to quantitatively analyze the influence of medium type on its metering performance. The instrument coefficient and indication error of the same vortex flowmeter are verified by water, diesel and air at different flow velocity points, and the measurement performance difference is analyzed which caused by the medium type. The experimental results are that the instrument coefficients by three media are some different under the conventional flow velocity, but not exceed 1/3 of the maximum allowable error, and the indication error is below 1.0 %, which meets the accuracy requirements. The conclusion is that the influence of the medium type on the measurement performance of the vortex flowmeter is small, and the result qualified by air, water or diesel can be used for other media, which can meets the requirements of the accuracy level.

Nuolin Xiang, Suna Guo, Chenguang Song, Longlong Wang
Dynamic characteristics of orifice flowmeter impulse response based on CFD simulation

Because of its simple structure and ability to measure in reverse, orifice flowmeters are widely used in petroleum, chemical and other fields. In the measurement, the pipeline flow state instability occurs, which has a greater impact on the measurement performance of the orifice flowmeter. In order to study the influence of dynamic flow on the dynamic characteristics of orifice flowmeter. Based on CFD simulation, the dynamic characteristics of orifice flowmeter with different throttling ratio (β) under sinusoidal pulsating flow conditions is studied. Through the simulation of the internal flow field of the orifice flowmeter under the conditions of 7 different frequencies and 4 different amplitude combinations, the differential pressure values under different working conditions are extracted to analyze the amplitude-frequency characteristics and phase-frequency characteristics. The results show that the frequency has a great influence on the dynamic characteristics of the orifice flowmeter. At the throttling ratio is 0.2, the flow rate is 6 m³/h and the amplitude is 1.2 m³/h, the orifice flowmeter amplitude-frequency characteristic linearity is as low as 1.9860 %, phase difference is as low as -7.56°.

Page 10 of 907 Results 91 - 100 of 9067